"""
输入M和N计算C(M,N)

Version: 0.1
Author: yuwl
Date：2023-12-16
"""

def fac(num):
	# 求阶乘
	result = 1
	for x in range(1, num + 1):
		result *= x
	return result

m = int(input('m = '))
n = int(input('n = '))
print(fac(m) // fac(n) // fac(m - n))